Field of the Invention
This invention relates to trailers such as boat and utility trailers and more particularly, to a load-bearing trailer dolly which connects a tongue-type trailer to a towing vehicle and bears weight from the trailer during towing. In a preferred embodiment, the trailer dolly is characterized by a an axle mount and axle assembly fitted with a pair of wheels which rest on the ground. A height-adjustable dolly frame provided on the axle mount includes a forwardly-extending drawbar for attachment to the drawbar receptacle on a towing vehicle and a rearwardly-extending hitch bar fitted with a hitch ball for engaging the trailer tongue on a trailer. A shock-absorbing spring is fitted between the axle mount and the dolly frame for cushioning the dolly frame on the axle mount and axle assembly as the trailer is towed behind the towing vehicle.
Trailers of various design such as boat trailers, utility trailers, travel trailers and the like are widely used to transport heavy vehicles or equipment. One of the problems frequently associated with using such trailers is that the forwardly-extending tongue on the trailer transmits much of the trailer weight to the hitch on the towing vehicle. This tends to overload the rear end of the towing vehicle and over time, results in excessive wear of the load-bearing elements on the vehicle, as well as adversely affecting vehicle stance and driveability.
A number of trailer dollies for connecting a trailer to a towing vehicle and bearing some of the trailer weight, are known in the art. Typical of these are the devices detailed in the following patents: U.S. Pat. No. 2,534,575, dated Dec. 19, 1950, to Conley, et al.; U.S. Pat. 2,828,973, dated Apr. 1, 1958; U.S. Pat. No. 2,844,389, dated Jul. 22, 1958; U.S. Pat. No. 3,281,161, dated Oct. 25, 1966; U.S. Pat. No. 3,865,405, dated Feb. 11, 1975; U.S. Pat. No. 4,253,679, dated Mar. 3, 1981; U.S. Pat. No. 4,491,338, dated Jan. 1, 1985.
An object of the present invention is to provide a load-bearing trailer dolly for connecting a tongue-type boat, utility or other trailer to a towing vehicle.
Another object of this invention is to provide a trailer dolly for connecting a trailer to a towing vehicle and bearing weight from the trailer.
Still another object of this invention is to provide a trailer dolly characterized by a dual-wheel axle assembly, a dolly frame mounted on the axle assembly, a drawbar extending forwardly from the dolly frame for coupling to the drawbar receiver on a towing vehicle and a hitch bar fitted with a hitch ball extending rearwardly from the dolly frame for removable coupling to the forwardly-extending trailer tongue on the trailer hitch of a trailer.
Yet another object of this invention is to provide a trailer dolly including a wheel-mounted axle, an axle mount extending upwardly from the axle, a dolly frame height-adjustably mounted on the axle mount by rotation of a crank-operated threaded rod, a drawbar extending forwardly from the dolly frame for coupling to the drawbar receiver of a towing vehicle, a hitch bar fitted with a hitch ball extending rearwardly from the dolly frame for coupling to the trailer tongue on a trailer, and a shock-absorbing spring interposed between the axle mount and the dolly frame for cushioning the dolly frame during towing of the trailer.
These and other objects of the invention are provided in a load-bearing trailer dolly which connects a tongue-type trailer to a towing vehicle and bears weight from the trailer during towing. In a preferred embodiment, the trailer dolly is characterized by an axle mounted on a pair of wheels and an axle mount upward-standing from the axle. A dolly frame height-adjustable on the axle mount by operation of a crank-operated threaded rod includes a forwardly-extending drawbar for attachment to the drawbar receptacle on a towing vehicle and a rearwardly-extending hitch bar fitted with a hitch ball for engaging the trailer tongue on a trailer. A shock-absorbing spring is fitted between the axle mount and the dolly frame for cushioning the dolly frame on the axle mount as the trailer is towed behind the towing vehicle.